Paint removing compositions

ABSTRACT

Water soluble paint remover compositions for the removal of uncured paint are disclosed which avoid the use of toxic organic solvent, in particular, methylene chloride. The inventive compositions comprise an organic carboxylic acid, N-methyl-2-pyrrolidone, and an alkylene glycol ether. Methods for use of the compositions are also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to novel compositions of matter which are usefulfor stripping or softening paint and methods for using suchcompositions. More particularly, the invention concerns paint removalcompositions which are water-soluble and environmentally safe.

2. Description of the Prior Art

The term "paint remover" as hereafter applied refers to chemicalcompositions which can strip or facilitate stripping of coatings, suchas, paint, lacquer, varnish, shellac, polyurethane finishes, enamels,and other coatings used to protect substrates and to beautify them. Ifapplied by wiping, a paint remover can also serve to "degloss" a finishso that it will be suitably prepared for application of a new coat ofpaint. When used on brushes or other coating applicators, some paintremovers can remove hardened paint and restore the brush to usablecondition.

Chemical paint removers have achieved considerable popularity becausethey are much easier to use than the non-chemical alternatives of blowtorches or power sanders. These chemical paint removers fall into twocategories. One category is a caustic based remover which is seldom usedin home applications because it is heated and requires dip tanks. Thiscategory has a deleterious effect on most kinds of wood, and oftendissolves glue holding the furniture together.

The most popular type of paint remover incorporates an organic chemicalsolvent base. A typical composition of such a paint remover is disclosedin U.S. Pat. No. 2,507,983, methylene chloride constituting 86% byweight of the mixture and methanol usually being added in smallerproportion to solubilize a methylcellulose thickener. Paint removersbased on methylene chloride are generally very effective on varnish andalkyd paint. They are less effective on lacquer and latex finishes.Unthickened removers which have high concentrations of methanol andbenzene are used for varnish removal. Wax is sometimes added to restrainthe rapid evaporation of the organic solvents.

A serious objection to such paint removers is their high degree oftoxicity, particularly due to the inhalation of vapors. Another seriousobjection is that they can burn the skin causing various degrees ofdermatitis, depending on the exposure.

A substantial body of literature directed to the extremely hazardousnature of methylene chloride has developed and it is clear that the useof this material in paint removers, while extensive in the past, must bediscontinued.

Other hazardous chemicals have commonly been used in paint removers,such as, methanol, benzene, xylene, hydrogen peroxide, phenol andcresols, and the like. All of these materials are highly disadvantageouswith respect to the environment or safety. The organic materials all aretoxic to various degrees and others of the materials named are so highlycorrosive or caustic that they can only be used under very restrictedconditions.

One attempt to avoid the presence of the environmentally unsuitablemethylene chloride or other organic solvents has been the inclusion inpaint removers of N-methyl-2-pyrrolidone. Thus. U.S. Pat. No. 4,128,810discloses the use of N-methyl-2-pyrrolidone in combination with a mixturof aromatic hydrocarbons having more than 6 carbon atoms. Thecomposition exhibits better safety characteristics, low toxicity, lowvolatility and does not burn the skin and also operates as a paintremover. However, a major disadvantage of this composition is the factthat it is not water soluble.

A significant problem occurs in the painting of vehicles, e.g.,automobiles and the like, wherein the parts for the automobiles arespray-painted in metal spraying booths. The interior of the booths mustbe cleaned, usually on a daily basis, and the paint on the surfaces ofthe interior of the booth, which is usually made of metal, removed. Theuse of a paint removal spray in such a situation is highly advantageous.However, it is understandable that the art is quite reluctant to utilizea paint remover containing the toxic materials outlined above. However,an additional problem is that if one uses a paint remover or stripperwhich is not water soluble, it is difficult to wash away the softenedpaint which, itself, of course, is not water soluble. Normally, it isdesired, after application of the paint remover and allowing it to standfor a sufficient amount of time to soften the paint, to hose or brushthe entire facility down Paint removers containing the organic materialsdo not work satisfactorily when the booths are hosed down and areincompletely removed.

Attempts to produce paint removers which are water soluble generallyrequire the presence of highly corrosive materials, such as, alkalimetal hydroxides. Typical of such materials is the composition disclosedin U.S. Pat. No. 4,368,082. Clearly, the corrosive nature of suchmaterials not only creates safety hazards, but also can be destructiveto the substrate from which the paint is being removed.

SUMMARY OF THE INVENTION

I have discovered a paint removing composition which is highly effectivefor the removal of a variety of different types of paints and which isenvironmentally safe, exhibits low toxicity, and furthermore, is watersoluble, therefore facilitating easy clean-up. More particularly, thecomposition of the present invention comprises an organic acid havingthe formula RCOOH wherein R is hydrogen, lower alkyl having from 1 to 10carbon atoms, halogen substituted lower alkyl having from 1 to 10 carbonatoms, hydroxy, and cyclic alkyl having from 4 to 6 carbon atoms andalkali metal salts thereof; an alkylene glycol ether, particularly thosewherein the alkylene group has 2 or 3 carbon atoms; and a compoundselected from the group consisting of five member ring lactones andlactams. Each of these components should be present in an amount suchthat the overall composition is effective in paint removal.

The composition of the present invention is particularly effective inpaint removing in the spray-painting of vehicle parts, because afterapplication of the paint remover, the interior of the spray boothutilized for the paint application may be hosed down with hot or coldwater.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Organic acids suitable for use in the present invention include thelower alkyl carboxylic acids and most preferred are formic acid, aceticacid, or mixtures thereof. Other acids which are suitable includechloroacetic, glycolic, and naphthenic acids. These acids are highlyeffective in the present composition, are readily available andrelatively inexpensive. Also, alkali metal salts of these acids may beused.

The second important component of the present invention is an alkyleneglycol ether. Included in this group are those ethers wherein thealkylene group has 2 or 3 atoms. Preferred are tripropyleneglycolmonomethyl ether, dipropyleneglycol monomehtyl ether and propyleneglycol monomethyl ether. Mixtures of these may also be used.

The third essential component of the composition is a five membered ringlactone or lactam. Preferred in this group is N-methyl-2-pyrrolidone,gamma-butyrolactone, 2-pyrrolidone, vinyl-pyrrolidone, and mixturesthereof.

The amount of each of the essential components in the final compositionmay vary within a certain range. What is important, however, is thateach be present in an amount sufficient to provide the overallcomposition with effectiveness in paint removal. Typically, thecomposition may contain from about 5 to 35, and preferably, from 10 to30 weight percent of the organic acid, from 30 to 65, and preferably,from 40 to 60 weight percent of the glycol ether, and from 10 to 50, andpreferably, from 15 to 40 weight percent of the lactone or lactam.

The composition of the present invention may also optionally containconventional wetting agents, corrosion inhibitors and thickeners.

Surface active agents may also be utilized in the composition. Thus,since the paint removal composition of the invention is water soluble,is amenable to flushing off the treated surface with water which may beapplied by a brush or hose, surface active agents may be used tomaintain any nonwater soluble components of the mixture, e.g., thepaint, in the form of an emulsion during flushing from the surface.Surface active agents of particular interest in compositions accordingto the present invention are those of a non-ionic nature which may, ifdesired, be of a biodegradable nature. Agents of the non-ionic typeinclude:

1. The polyethylene oxide condensates of alkylphenols, e.g., thecondensation products of alkylphenols or dialkyl phenols wherein thealkyl group contains from about 6 to about 12 carbon atoms in eitherbranched chain or particularly straight chain configuration, forexample, octyl cresol, octyl phenol or nonyl phenol, with ethyleneoxide, the said ethylene oxide being present in amounts equal to about 5to about 25 moles of ethylene oxide per mole of alkylphenol.

2. Partial esters formed by the reaction of fatty acids, for example ofabout 8 to about 18 carbon atoms, with polyhydric alcohols, for example,glycerol, glycols, such as, mono-, di-, tetra- and hexaethyleneglycol,sorbitan, etc; and similar compounds formed by the direct addition ofvarying molar ratios of ethylene oxide to the hydroxy group of fattyacids.

3. The condensation products of fatty acid partial esters with ethyleneoxide, such as, fatty acid esters of polyoxyethylene sorbitan andsorbitol containing from about 3 to about 80 oxyethylene units permolecule and containing fatty acid groups having from about 8 to about18 carbon atoms.

4. The condensation products of aliphatic alcohols having from about 8to about 18 carbon atoms in either straight chain or branched chainconfiguration, for example, oleyl or cetyl alcohol, with ethylene oxide,the said ethylene oxide being present in amounts equal to about 30 toabout 60 moles of ethylene oxide per mole of alcohol.

Of these classes of non-ionic surface active agents, the condensates ofethylene oxide with alkyl phenols are of especial interest. Preferredsurface active agents of this class are those condensates wherein 1 moleof the alkyl phenol is condensed with from 5 to 15 moles of ethyleneoxide, particularly when the alkyl phenol is octyl or especially nonylphenol. Examples of surface active agents of this type which may be usedare those supplied under the following trade names:

    ______________________________________                                        Name         Approximate Chemical Constitution                                ______________________________________                                        Antaron ®                                                                              monocarboxyl cocoimidazoline                                     Igepon ® alkyl sulforamides                                               Alipal ® ammonium salt of ethoxylate sulfate                              Igepal ® ethoxylated alkylphenol                                          Emulphogene ®                                                                          tridecyloxypoly(ethyleneoxy)ethanol                              Span 40 ®                                                                              sorbitan monopalmitate                                           Parasyn ®                                                                              hydrogenated castor oil                                          Miraniol ®                                                                             cocoamphodipropionate                                            Trydet ® polyethoxylated fatty acid ester.                                ______________________________________                                    

Normally, if surface active agents are included in the composition, theyare included in an amount from about 1 to 8 weight percent, andpreferably, from about 2 to 4 weight percent.

Corrosion inhibitors may also be included in the inventive composition.Such corrosion inhibitors are conventional. If such corrosion inhibitorsare included in the inventive composition, they are normally present inan amount from about 0.5 to 2 weight percent, and preferably, from about0.9 to 1.1 weight percent. Typical corrosion inhibitors include Rodine®from Amchem, Ambler, Pa.

Thickeners may also be included in the inventive composition. Thepreferred thickeners or gelling agents cellulose derivatives having theproperty of both water and organic solvent solubility. Cellulosederivatives of this type which are of particular interest are thoseether derivatives containing etherifying groups selected fromhydroxyalkyl groups and groups derived therefrom, such etherifyinggroups containing preferably up to about 5 or 6 carbon atoms. Thegelling agent may also comprise cellulose ether derivatives which, inaddition to etherifying groups selected from hydroxyalkyl groups andgroups derived therefrom, contain other types of etherifying groups,especially small alkyl groups of, for example, one or two carbon atoms.However, such etherifying groups generally confer properties upon thecellulose derivative which are less acceptable for the present purpose,and the gelling agent is therefore conveniently substantially restrictedto cellulose ether derivatives containing etherifying groups selectedfrom hydroxyalkyl groups and groups derived therefrom.

Etherifying groups consisting of or derived from hydroxyalkyl groupscontaining up to 5 carbon atoms, particularly, 2, 3 or 4 carbon atoms,are of especial value. The hydroxypropyl celluloses, for example, havebeen found to be of particular value in giving a substantiallytransparent gel system with a suitable solvent system and in impartingquite adequate thickening and film-forming properties in their own rightwithout the need of any other agents for these purposes. Conveniently,the hydroxypropyl group in such celluloses is derived from isopropanolrather than n-propanol but a number of variations in structure arepossible even when this is the case. Thus, not all of the free hydroxygroups of the cellulose need necessarily be substituted and, if desired,the hydroxy groups of certain hydroxypropyl groups may, in turn, besubstituted by a further hydroxypropyl group (as for example, in theKlucel materials described below). Hydroxypropyl celluloses employed incompositions according to the present invention conveniently havemolecular weights in the range from about 50,000 to about 1,000,000,preferably from about 800,000 to 1,000,000.

One form of hydroxypropyl cellulose which has been used with advantageis marketed under the trade name Klucel H and is based upon repeatingunits containing a pair of anhydroglucose groups in which 5 of the freehydroxyl groups are etherified, the units being of the type: ##STR1##

Klucel H has a similar chemical structure to Klucel MS 3.0, which mayalso be used, but is of higher molecular weight, and possessesparticular advantages in terms of the viscosity of its solutions. Thus,a 1% solution of Klucel H in water has a viscosity in the range from1,500 to 2,500 units and in ethanol the range is 1,000 to 2,500 unitswhile solutions of Klucel MS 3.0, particularly in ethanol, have a lowerviscosity. The property of possessing a substantially similar viscosityin organic solvent and aqueous solutions is a valuable one for gellingagents used in compositions according to the present invention. Theproportion of gelling agent required in the compositions in order togive good gels, depends in part on the molecular weight of the gellingagent used, the usual range being from 0.25% to 10% or even 15%, 18% or20%. Thus, for example, with the usual proportion of gelling agent offrom about 0.25% or 0.5% upwards is suitable for high molecular weightmaterials and of from about 3% upwards is suitable for low molecularweight materials. For high molecular weight materials, for example ofmolecular weights of 800,000 to 1,000,000, a proportion of above 1.5% ispreferably avoided as it leads to a gel of too great a viscosity. Withlow molecular weight materials, larger proportions may be used beforesuch a position is reached and, if the molecular weight is low enough,amounts of up to 10% or even 20% or more may be used. It will beappreciated, however, that the use of a smaller amount of material ofhigher molecular weight is generally to be preferred.

A particularly preferred composition is about 15 to 40 weight percentN-methyl-2-pyrrolidone, about 40 to 60 weight percent triproyyleneglycolmonomethylether and 10 to 30 weight percent acid, with the acidcomponent being composed of about one to two parts of formic acid andabout four to three parts of acetic acid.

The amount of thickener utilized is usually from about 0.5 to 2 weightpercent, with 0.8 to 1.1 weight percent being preferred.

In the following examples, a variety of compositions were tested fortheir paint removing ability. These tests were carried out by firstphysically formulating the compositions, i.e., by mixing all of theingredients together except for the thickener which is thereafter addedslowly while stirring. The pH and viscosity of each of formulation wasthen measured.

Each such composition was then subjected to a SAG test using a LenetaSAG meter by applying the composition to a black varnished test card.The card was placed in a vertical position for 15 seconds. The SAGnumber indicates the thickness of the film of the specific formulationwhich will not flow down one millimeter. The purpose of this test is toprovide an indication of the tendency of a given stripper composition toflow downwardly when applied to a vertical surface, as on the walls of aspray booth.

The paint stripping ability of the compositions was measured as follows:

Cold rolled steel coupons (1×3 inches, available from Q-Panel) werepainted with white or blue automotive paint (DuPont melamineformaldehyde acrylic paint). The paint was applied by spraying onto bothsides of the metal coupon. The amount of paint applied to each couponwas 0.7 mils thick.

The paint was not allowed to cure. Within seven days after applicationof the paint (normally within four days to insure against curing) thepainted coupon was immersed into the test formulation, withdrawn, andplaced against a vertical surface.

At various time periods after this placement, i.e., 5 or 15 minutes, thestripper and loosened paint were removed from the coupon by rinsing itunder a stream of tap water. The gloss of the coupon was then measuredutilizing a Gardner gloss meter.

An unpainted coupon gives a gloss reading of greater than 100. Any paintresidue remaining on the coupon reduces this reading and is anindication of the amount of paint remaining which corresponds to therelative effectiveness of the stripper. After 24 hours, the gloss of thecoupon was measured again. This reading indicates loss in reflectivityof the metal due to rusting.

                                      TABLE 1                                     __________________________________________________________________________                                           SURFACE                                                         METHYL-       ACT. AGENT                                                                            CORROSION                      Test         FORMIC      NAPHTA-                                                                             THICKENER                                                                             IGEPAL ®                                                                          INHIBITOR                      No.                                                                              NMP TPM                                                                              PM ACID  XYLENE                                                                              LENE  KLUCEL H ®                                                                        CO-710  RODINE ®                                                                          TEA                    __________________________________________________________________________    1  40.0                                                                              30.0  25.0  5.0         0.8     2.0     0.5     2.0                    2  40.0   30.0                                                                             25.0  5.0         0.8     2.0     0.5     2.0                    3  40.0                                                                              30.0  25.0        5.0   0.8     2.0     0.5     2.0                    4  40.0   30.0                                                                             25.0        5.0   0.8     2.0     0.5     2.0                    5  45.0                                                                              30.0  25.0              0.8     2.0     0.5     2.0                    6  30.0                                                                              45.0  25.0              0.8     2.0     0.5     2.0                    __________________________________________________________________________     NMP is N--methyl2-pyrrolidone                                                 TPM is tripropyleneglycol monomethyl ether                                    PM is propyleneglycol monomethyl ether                                        TEA is triethanol amine                                                  

                  TABLE 2                                                         ______________________________________                                        Test       BROOKFIELD        WHITE GLOSS                                                                              BLUE                                  No.  pH    VISCOSITY    SAG  15 Min.                                                                              5 Min.                                                                              GLOSS                               ______________________________________                                        1    2.4   4,300        20.0 94.0         100.0                               2    2.6   1,900        16.0 93.5         100.0                               3    2.4   3,500        20.0 97.0         100.0                               4    2.5   2,000        18.0 80.0         100.0                               5    2.4   4,100        20.0        92.5                                      6    2.0   4,400        30.0        90.0                                      ______________________________________                                    

The data in Tables 1 and 2 shows that the paint removing properties ofcompositions in accordance with the present invention are at leastequivalent to or better than those compositions which contain organicsolvents, such as, xylene or naphthalene. Thus, the organic solvents areknown to improve the penetration of a composition into the paint. Thegloss measurements after the stripping composition had remained on thepainted coupon for 15 minutes are shown. However, with the compositionsin accordance with the present invention, i.e., test No. 5 and 6, whreinneither xylene nor naphthalene was utilized, superior paint strippingproperties were achieved only after five minutes of contact.

A series of experiments was carried out to study the effect of aceticacid versus formic acid in terms of paint removal. The compositions usedand the results obtained are set forth in Tables 3 and 4. As can be seentherein, acetic acid is as effective as formic acid in stripping paint.This is important because acetic acid is somewhat less corrosive thanformic acid. Note that the gloss with TAL-STRIP® (a commercial methylenechloride containing paint stripper) is halved because of the extensiverusting of the surface after the use of this stripper.

An additional series of experiments was carried out using varyingamounts of NMP and glycol ether components. Also, compositionscontaining sodium formate rather than formic acid or acetic acid wereutilized. The compositions used in these experiments are shown in Table3 and the results obtained are shown in Table 4.

                                      TABLE 3                                     __________________________________________________________________________    SPRAY BOOTH STRIPPERS MELAMINE FORMALDEHYDE ACRYLATE PAINTS FORMULATIONS                       ACID       SODIUM KLUCEL                                                                              IGEPAL ®                         No.                                                                              NMP     TPM                                                                              PM FORMIC                                                                              ACETIC                                                                             FORMATE                                                                              H ®                                                                             CO-710 RODINE ®                                                                         TEA                    __________________________________________________________________________     7 35.0    40.0  25.0              0.8   2.0    0.5    2.0                     8 40.0    35.0  25.0              0.8   2.0    0.5    2.0                     9 45.0    30.0  25.0              0.8   2.0    0.5    2.0                    10 50.0    25.0  25.0              0.8   2.0    0.5    2.0                    11 55.0    20.0  25.0              0.8   2.0    0.5    2.0                    12 32.0    42.0  26.0              0.9   2.0    1.5    2.0                    13 42.0    36.0  22.0              0.9   2.0    1.5    2.0                    14 42.0    32.0  26.0              0.9   2.0    1.5    2.0                    15 44.0    32.0  24.0              0.9   2.0    1.5    2.0                    16 46.0    32.0  22.0              0.9   2.0    1.5    2.0                    17 44.0    30.0  26.0              0.9   2.0    1.5    2.0                    18 52.0    22.0  26.0              0.9   2.0    1.5    2.0                    19 32.0       42.0     26.0        0.9   2.0    1.5    2.0                    20 42.0       36.0     22.0        0.9   2.0    1.5    2.0                    21 42.0       32.0     26.0        0.9   2.0    1.5    2.0                    22 44.0       32.0     24.0        0.9   2.0    1.5    2.0                    23 46.0       32.0     22.0        0.9   2.0    1.5    2.0                    24 44.0       30.0     26.0        0.9   2.0    2.5    2.0                    25 52.0       22.0     26.0        0.9   2.0    1.5    2.0                    26 52.0    22.0  26.0              1.0   2.0    1.5    3.0                    27 42.0    32.0  26.0              1.0   2.0    2.0    1.0                    28 42.0    32.0  13.0       13.0   1.0   2.0    2.0    3.0                    29 52.0    22.0  13.0       13.0   0.9   2.0    2.0    3.0                    30 42.0    32.0  26.0              0.9   2.0    1.5    3.0                    31 52.0    22.0  13.0       13.0   1.0   2.0    1.5    1.0                    32 52.0    22.0  26.0              0.9   2.0    2.0    1.0                    33 42.0    32.0  13.0       13.0   0.9   2.0    1.5    1.0                    34 TAL-STRIP ®                                                            __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________    SPRAY BOOTH STRIPPERS MELAMINE FORMALDEHYDE                                   ACRYLATE PAINTS PERFORMANCE PROPERTIES                                                    BROOKFIELD   GLOSS BLUE 24 HRS.                                   No. pH      VISCOSITY SAG                                                                              15 MIN.                                                                             GLOSS                                                                              GLOSS                                     __________________________________________________________________________     7  2.3     5,500     20.0                                                                             10.0       10.0                                       8  2.4     5,500     25.0                                                                             30.0       24.0                                       9  2.6     6,800     25.0                                                                             5.0        5.0                                       10  2.7     4,900     20.0                                                                             6.0        6.0                                       11  2.8     5,100     25.0                                                                             7.5        7.0                                       12  2.2     7,100     25.0                                                                             5.0   59.0 6.0                                       13  2.9     5,250     25.0                                                                             6.5   78.0 5.0                                       14  2.7     6,400     25.0                                                                             84.0  63.5 81.0                                      15  2.7     5,100     30.0                                                                             16.5  76.0 13.5                                      16  2.8     6,100     25.0                                                                             5.0   88.5 5.0                                       17  2.6     5,950     30.0                                                                             24.0  100.0                                                                              27.5                                      18  2.6     5,100     25.0                                                                             95.0  82.0 100.0                                     19  4.4     1,850     20.0                                                                             59.0  100.0                                                                              57.5                                      20  4.8     2,650     25.0                                                                             13.5  100.0                                                                              18.0                                      21  4.5     3,000     20.0                                                                             45.0  100.0                                                                              51.0                                      22  4.8     1,400     18.0                                                                             5.5   100.0                                                                              5.0                                       23  4.8     2,500     20.0                                                                             5.0   100.0                                                                              5.0                                       24  4.5     2,200     20.0                                                                             52.5  100.0                                                                              57.5                                      25  4.8     1,800     20.0                                                                             11.0  100.0                                                                              8.5                                       26  2.7     2,500     25.0                                                                             85.0       82.5                                      27  2.4     4,100     20.0                                                                             83.0       78.5                                      28  4.6     4,200     30.0                                                                             58.5       64.5                                      29  4.7     3,700     18.0                                                                             17.5       18.5                                      30  2.6     4,200     25.0                                                                             64.5       63.5                                      31  4.6     4,700     25.0                                                                             67.5       65.0                                      32  2.6     2,700     25.0                                                                             82.0       87.5                                      33  4.3     4,550     30.0                                                                             100.0      100.0                                     34  TAL-STRIP ®      52.5       25.0                                      __________________________________________________________________________

                                      TABLE 5                                     __________________________________________________________________________    STRIPPER FORMULATIONS                                                                   ACID           CHLORO-             IGEPAL ®                     No.                                                                              NMP PM FORMIC                                                                              ACETIC   ACETIC                                                                              GLYCOLIC                                                                             KLUCEL ®                                                                         CO-710 RODINE ®                                                                         TEA                __________________________________________________________________________    34 44.0                                                                              30.0                                                                             26.0                        0.9    2.0    1.5    2.0                35 44.0                                                                              30.0     26.0                  0.9    2.0    1.5    2.0                36 44.0                                                                              30.0     23.0     3.0          0.9    2.0    1.5    2.0                37 44.0                                                                              30.0                    26.0   0.9    2.0    1.5    2.0                38 44.0                                                                              30.0                                                                             22.0  (+4.0                 0.9    2.0    1.5    2.0                                NaFORMATE)                                                    __________________________________________________________________________

                  TABLE 6                                                         ______________________________________                                        PERFORMANCE PROPERTIES                                                                       BROOKFIELD          GLOSS                                      No.     pH     VISCOSITY      SAG  15 MIN.                                    ______________________________________                                        34      2.75   2,400          18.0 100.85                                     35      5.20   2,200          18.0 100.00                                     36      4.20   2,350          20.0 100.00                                     37      2.65   3,700          20.0 100.00                                     38      3.70   2,800          20.0 100.00                                     ______________________________________                                    

The results in Tables 5 and 6 show that effective paint strippingresults can be obtained utilizing a variety of content ranges of each ofthe three required components of the inventive composition. In addition,this data shows that sodium formate may be utilized in place of aportion of the formic acid to be produce a composition which strips thepaint effectively. The formulation obtained with the sodium formatecomposition provides a higher pH composition with a somewhat decreasedtendency for rusting of cold rolled steel.

I claim:
 1. A method for removing uncured paint from a substratecomprising(1) applying to said substrate in glon liquid form a paintremoving effective amount of a water-soluble composition consistingessentially of(a) an organic acid having the formula RCOOH wherein R ishydrogen, lower alkyl having from 1 to 10 carbon atoms, halogensubstituted lower alkyl having from 1 to 10 carbon atoms, hydroxy andcyclic alkyl having from 4 to 6 carbon atoms, and alkali metal salts ofsaid acids; (b) an alkylene glycol ether; and (c) a five member ringlactone or lactam; and then (2) washing the substrate with water toremove said composition and aint from the substrate.
 2. A method forremoving uncured paint from a substrate comprising(1) applying to saidsubstrate in glon liquid form a paint removing effective amount of awater-soluble composition consisting essentially of(a) from about 15 to40 weight percent N-methyl-2-pyrrolidone; (b) from about 40 to 60 weightpercent tripropyleneglycol methyl ether; and p2 (c) from about 10 to 30weight percent of an organic acid mixture composed of about one to twoparts formic acid and about four to three parts acetic acid; and then(2) washing the substrate with water to remove said composition andpaint from the substrate.
 3. The method of claim 1 wherein the amount oforganic acid is from about 5 to 35 weight percent, the amount of glycolether is about 30 to 65 weight percent, and the amount of lactone orlactam is about 15 to 40 weight percent.
 4. The method of claim 3wherein the amount of organic acid is from about 10 to 30 weightpercent, the amount of glycol ether is from about 40 to 60 weightpercent, and the amount of lactone or lactam is from about 15 to 40weight percent.
 5. The method of claim 1 wherein the composition furthercomprises thickeners, surface active agents, corrosion inhibitors, andmixtures thereof.
 6. The composition of claim 1 wherein the lactone orlactam is selected from the group consisting of N-methyl-2-pyrrolidone,gamma-butyrolactone, 2-pyrrolidone, vinyl-pyrrolidone, and mixturesthereof.
 7. The method of claim 1 wherein the organic acid is selectedfrom the group consisting of formic, acetic, chloroacetic, glycolic,naphthenic, and mixtures thereof.
 8. The composition of claim 1 whichfurther contains an alkali metal salt of said organic acid.
 9. Themethod of claim 1 wherein the organic acid is selected from the groupconsisting of formic and acetic.
 10. The method of claim 9 wherein thealkylene glycol ether has 2 or 3 carbon atoms in the alkylene portion.11. The method of claim 9 wherein alkylene glycol ether is selected fromthe group consisting of tripropyleneglycol monomethyl ether,dipropyleneglycol monomethyl ether, and propyleneglycol monomethylether.
 12. The method of claim 2 wherein the organic acid mixture iscomposed of one part formic acid and four parts acetic acid.